A permanent magnet synchronous motor controller for washing machine

Abstract

The present invention discloses a permanent magnet synchronous motor controller for a washing machine, which belongs to the technical field of washing machines, and aims to solve the defect that the sampling current signal of the inverter of the existing washing machine controller is easily distorted. The controller includes a microcontroller digital operation unit, an inverter unit, and a current sampling unit. The current sampling unit includes an anti-distortion processing circuit. The current sampling unit collects the three-phase lower bridge arm current signal of the inverter unit and performs anti-distortion processing on the current signal through the anti-distortion processing circuit and then sends it to the microcontroller digital operation unit. The microcontroller digital operation unit forms a high-frequency carrier PWM signal for auxiliary driving of the inverter unit. The anti-distortion processing circuit is arranged on the current sampling unit, which can reduce the distortion degree of the current signal received by the microcontroller digital operation unit from the inverter unit, improve the accuracy of the current signal, and improve the accuracy of the controller control.

Description

Technical Field

[0001] The invention belongs to the technical field of washing machines and relates to a permanent magnet synchronous motor controller for a washing machine. Background Art

[0002] Existing washing machines usually use a controller to control the working mode of the washing machine, such as the dehydration mode and the washing mode. The controller includes a microcontroller digital operation unit, an inverter unit, and a current sampling unit connected between the microcontroller digital operation unit and the inverter unit. The current sampling unit samples the current of the inverter unit and transmits the current sampling signal to the microcontroller digital operation unit to assist the microcontroller digital operation unit in controlling the inverter unit. Since the transmission distance from the inverter unit to the microcontroller digital operation unit is long, the current sampling signal is easily interfered during the transmission process, which easily leads to a reduction in the control performance of the entire washing machine control system. Summary of the invention

[0003] The present invention aims to solve the problem of the prior art by providing a permanent magnet synchronous motor controller for a washing machine, and aims to solve the defect that the sampling current signal of the inverter of the prior washing machine controller is easily distorted.

[0004] The present invention is achieved in that:

[0005] A permanent magnet synchronous motor controller for a washing machine, characterized by comprising:

[0006] A microcontroller digital operation unit is used to control the start and stop and operation mode of the washing machine motor;

[0007] The inverter unit generates a high-frequency modulated carrier signal to drive the motor according to the driving signal of the digital operation unit of the microcontroller;

[0008] The current sampling unit includes an anti-distortion processing circuit. The current sampling unit collects the three-phase lower bridge arm current signal of the inverter unit and performs anti-distortion processing on the current signal through the anti-distortion processing circuit and then sends the anti-distortion signal to the microcontroller digital operation unit. The microcontroller digital operation unit forms a high-frequency carrier PWM signal based on the signal to assist in driving the inverter unit.

[0009] The anti-distortion processing circuit includes a common-phase input unit, an operational amplifier main unit, an operational amplifier feedback unit, and an output signal processing unit; the common-phase input unit is connected between the inverter unit and the common-phase input terminal of the operational amplifier main unit, the operational amplifier feedback unit is connected between the inverting input terminal of the operational amplifier main unit and the output terminal of the operational amplifier main unit, and the output signal processing unit is connected between the output terminal of the operational amplifier main unit and the microcontroller digital operation unit.

[0010] The non-inverting input unit includes a resistor R1, a resistor R2 and a resistor R3 connected in series in sequence, the resistor R3 is connected in parallel with an electronic switch K1, and a common point of the resistor R1 and the resistor R2 is connected to the non-inverting input end of the operational amplifier main unit; the operational amplifier feedback unit includes a capacitor C2 and a resistor R5 and a resistor R6 connected in series with each other, the resistor R6 is connected in parallel with an electronic switch K2, one end of the capacitor C2 is connected to a common point of the resistor R5 and the inverting input end of the operational amplifier feedback unit, and the other end is connected to a common point of the resistor R6 and the output end of the operational amplifier main unit, the inverting input end of the operational amplifier main unit is grounded through R4, and the electronic switch K1 and the electronic switch K2 are commonly connected to the microcontroller digital operation unit.

[0011] The in-phase input unit is powered by a 1.65V pull-up bias power supply, the positive power supply pin of the operational amplifier main unit is connected to a 3.3V power supply, and the negative power supply pin of the operational amplifier main unit is grounded.

[0012] The resistance R1-R6 is governed by the following relationship:

[0013] R1=R4, R3=R6=(k-1)*R2=(k-1)*R5, where the value of k is 1-7.

[0014] The non-inverting input unit includes a capacitor C1 connected to the ground.

[0015] The output signal processing unit includes a resistor R7 and a capacitor C3 connected to the ground.

[0016] The controller further comprises:

[0017] A power input unit is used to provide a single-phase mains power interface to the controller;

[0018] The main circuit unit is used to perform buffering, EMC processing, sorting and smoothing processing on the input power;

[0019] The bus sampling unit is used to collect the bus voltage of the controller in the current state;

[0020] The LDO circuit unit performs two-stage voltage reduction on the bus voltage after smoothing to obtain a 15V power supply signal and a 3.3V power supply signal, providing a non-isolated weak power supply signal for the controller;

[0021] Communication control unit, used for instruction interaction between the user host computer and the microcontroller digital operation unit;

[0022] The program burning unit is used for the instruction interaction between the manufacturer's host computer and the microcontroller digital operation unit.

[0023] The main circuit unit comprises a current limiting resistor and a relay connected in parallel with the current limiting resistor, and the relay is connected to a digital operation unit of a microcontroller.

[0024] The inverter unit comprises an intelligent power module IPM and a back-mounted heat sink, wherein the intelligent power module IPM is fixed on the heat sink and is welded on a PCB board.

[0025] A permanent magnet synchronous motor controller for a washing machine provided by the present invention is provided with an anti-distortion processing circuit on a current sampling unit, which can reduce the distortion degree of the current signal received by the microcontroller digital operation unit from the inverter unit, improve the accuracy of the current signal, and improve the accuracy of the controller control. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the topological structure of the controller;

[0027] Figure 2 Schematic diagram of the circuit structure of the anti-distortion processing circuit.

[0028] Notes on the accompanying drawings: U9-1, input interface unit; U9-2, in-phase input unit; U9-3, operational amplifier main unit; U9-4, operational amplifier feedback unit; U9-5, output signal processing unit; U9-6, output interface unit. DETAILED DESCRIPTION

[0029] The following will further describe the specific implementation of the present invention in combination with the accompanying drawings to make the technical solution of the present invention easier to understand and grasp. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] This embodiment provides a permanent magnet synchronous motor controller for a washing machine. Figure 1 As shown, it includes a microcontroller digital operation unit, an inverter unit, a current sampling unit, a power input unit, a main circuit unit, a bus sampling unit, an LDO circuit unit, a communication control unit and a program burning unit.

[0031] The power input unit is used to provide a single-phase mains power interface for the controller. The power input unit includes a safety circuit and a single-phase three-wire input circuit. The power input unit is connected to the main circuit unit.

[0032] The main circuit unit includes a power-on buffer circuit, an EMC circuit, a rectifier circuit and a smoothing circuit, which are used to perform buffering, EMC processing, sorting and smoothing processing on the input power supply. The power-on buffer circuit includes a current limiting resistor and a relay connected in parallel to the current limiting resistor, and the relay is connected to the digital operation unit of the microcontroller. The bus sampling unit is used to collect the bus voltage of the controller after being processed by the smoothing circuit in the current state, and send it to the microcontroller digital operation unit after voltage division and filtering through the voltage divider resistor. When the microcontroller digital operation unit detects that the bus voltage reaches the threshold for more than three seconds, the relay of the power-on buffer circuit closes and short-circuits the current limiting resistor.

[0033] The LDO circuit unit performs two-stage voltage reduction on the bus voltage after smoothing to obtain a 15V power signal and a 3.3V power signal, providing a non-isolated weak power signal for the controller. The 3.3V power signal is used to power the microcontroller digital operation unit, the communication control unit and the program burning unit. The 15V power signal is used to power the current sampling unit and the inverter unit. The bus also powers the motor through the inverter unit.

[0034] The communication control unit is used for the instruction interaction between the user host computer and the microcontroller digital operation unit. The user can send instructions to the microcontroller digital operation unit through the user host computer, so that the microcontroller digital operation unit controls the start and stop and operation mode of the washing machine motor. The operation mode includes washing mode and dehydration mode. The user host computer can also display the operation status of the washing machine.

[0035] The inverter unit generates a high-frequency modulated carrier signal to drive the motor according to the driving signal of the microcontroller digital operation unit. The inverter unit includes an intelligent power module IPM and a back-mounted heat sink. The intelligent power module IPM is fixed on the heat sink and welded together on the PCB board. The intelligent power module IPM is first fixed on the heat sink to form an assembly, and then the assembly is welded to the PCB board, which can reduce the stress of each pin of the intelligent power module IPM, thereby improving the reliability of the product.

[0036] The program burning unit is used for the instruction interaction between the manufacturer's host computer and the microcontroller digital operation unit. For example, the manufacturer debugs and injects programs into the washing machine through the manufacturer's host computer.

[0037] The current sampling unit includes an anti-distortion processing circuit. The current sampling unit collects the current signal of the three-phase lower bridge arm of the inverter unit and sends the current signal to the microcontroller digital operation unit after anti-distortion processing through the anti-distortion processing circuit. The microcontroller digital operation unit forms a high-frequency carrier PWM signal based on this to assist in driving the inverter unit.

[0038] The microcontroller digital operation unit has an MCU, which can store a speed estimation program and a weight estimation program. It can estimate the motor running speed and the weight of the clothes according to the current signal fed back by the current sampling unit, and estimate the weight of the clothes to provide the user with a recommended washing plan.

[0039] like Figure 2 As shown, the anti-distortion processing circuit includes an input interface unit U9-1, a common-phase input unit U9-2, an operational amplifier main unit U9-3, an operational amplifier feedback unit U9-4, an output signal processing unit U9-5, and an output interface unit U9-6Iout; the common-phase input unit is connected between the inverter unit and the common-phase input terminal of the operational amplifier main unit U9-3, the operational amplifier feedback unit U9-4 is connected between the inverting input terminal of the operational amplifier main unit U9-3 and the output terminal of the operational amplifier main unit U9-3, and the output signal processing unit U9-5 is connected between the output terminal of the operational amplifier main unit U9-3 and the microcontroller digital operation unit.

[0040] Specifically, the input interface unit U9-1 includes a sampling current input interface Iin and a control signal interface mUc, the sampling current input interface is connected to the inverter unit, and the control signal interface is connected to the microcontroller digital operation unit.

[0041] The in-phase input unit U9-2 includes a resistor R1, a resistor R2 and a resistor R3 connected in series in sequence, a sampling current input interface is connected to the resistor R1, and a common point of the sampling current input interface and the resistor R1 is grounded through a capacitor C1, and the capacitor C1 is used to filter out high-frequency carrier signals. The resistor R3 is connected in parallel with an electronic switch K1, and a common point of the resistor R1 and the resistor R2 is connected to the in-phase input terminal of the operational amplifier main unit U9-3, and the in-phase input unit U9-2 is powered by a 1.65V pull-up bias power supply.

[0042] The operational amplifier feedback unit U9-4 includes a capacitor C2 and resistors R5 and R6 connected in series, the resistor R6 is connected in parallel with an electronic switch K2, one end of the capacitor C2 is connected to the common point of the resistor R5 and the inverting input end of the operational amplifier feedback unit U9-4, the capacitor C2 is used to eliminate high-frequency self-excitation and expand the bandwidth of the system, and the other end is connected to the common point of the resistor R6 and the output end of the operational amplifier main unit U9-3, the inverting input end of the operational amplifier main unit U9-3 is grounded through R4, and the electronic switch K1 and the electronic switch K2 are connected to the microcontroller digital operation unit. The electronic switches K1 and K2 are linked electronic switches, which are controlled by the microcontroller digital operation unit to be turned on or off at the same time.

[0043] The output signal processing unit U9-5 includes a resistor R7 and a grounded capacitor C3, where the capacitor C3 is an output filter capacitor. One end of the resistor R7 is connected to the output end of the operational amplifier main unit U9-3, and the other end of the resistor R7 is grounded through the capacitor C3 and connected to the output interface unit U9-6Iin, which is connected to the microcontroller digital operation unit.

[0044] The positive power supply pin of the operational amplifier main unit U9 - 3 is connected to a 3.3V power supply, and the negative power supply pin of the operational amplifier main unit U9 - 3 is grounded.

[0045] The resistors R1-R6 can be plug-in resistors, chip resistors, or resistors of different resistance values ​​that are appropriately connected in series, in parallel, or in series-parallel splitting and combination.

[0046] The resistors R1-R6 are constrained by the following relationship: R1=R4, R3=R6=(k-1)*R2=(k-1)*R5, where k is 1.5-7. In the washing mode, the microcontroller digital operation unit controls the electronic switches K1 and K2 to remain in the open state, and the resistors R3 and 6 participate in the current amplification calculation. The current amplification coefficient is determined by k*R5 / R4, where k is 1.5-7. In the dehydration mode, the microcontroller digital operation unit controls the electronic switches K1 and K2 to remain in the closed state, and the resistors R3 and R6 are short-circuited by the electronic switches K1 and K2 and do not participate in the current amplification calculation. The current amplification coefficient is determined by k*R5 / R4, where k is 1.

[0047] The three-resistance lower bridge arm of the three-phase U, V, and W each corresponds to an anti-distortion processing circuit, and the three-phase anti-distortion processing circuits share a control signal interface mUc. The input interface unit is independent of each other for three phases, and the output interface unit Iout is independent of each other for three phases, and each independently sends the three ADC sampling ports of the microcontroller digital operation unit. The anti-distortion processing circuits of the three-phase current sampling units have the same processing type and processing mechanism, and the circuit structures are independent of each other.

[0048] The current sampling signal in the dehydration mode is about 5-7 times that in the washing mode. If the same proportional amplification factor is used, the current signals in the washing mode and the dehydration mode are very likely to be at the two ends of the same amplification interval, which makes it extremely easy for the current signal in a certain state to enter the nonlinear interval and distort. In particular, the current signal in the washing mode is relatively weak and is more easily interfered during the transmission process, resulting in reduced control performance of the entire washing machine control system. The current signals in the washing mode and the dehydration mode are processed differently, and the amplification factors of the three-phase current sampling of U, V, and W are adjusted and controlled according to the working state of the washing machine. In particular, the current sampling signal is relatively weak in the washing mode, and a relatively high current amplification factor is used to improve the anti-interference ability; the current sampling signal is relatively strong in the dehydration mode, and a relatively low current amplification factor is used to prevent the collected signal from being clipped and distorted.

Claims

1. A permanent magnet synchronous motor controller for a washing machine, characterized in that: include: A microcontroller digital operation unit is used to control the start and stop and operation mode of the washing machine motor; The inverter unit generates a high-frequency modulated carrier signal to drive the motor according to the driving signal of the digital operation unit of the microcontroller; A current sampling unit, wherein the current sampling unit includes an anti-distortion processing circuit, the current sampling unit collects the current signal of the three-phase lower bridge arm of the inverter unit, performs anti-distortion processing on the current signal through the anti-distortion processing circuit, and then sends the current signal to the microcontroller digital operation unit, and the microcontroller digital operation unit forms a high-frequency carrier PWM signal based on the current signal to assist in driving the inverter unit; The anti-distortion processing circuit comprises a non-inverting input unit, an operational amplifier main unit, an operational amplifier feedback unit, and an output signal processing unit; the non-inverting input unit is connected between the inverter unit and the non-inverting input end of the operational amplifier main unit, the operational amplifier feedback unit is connected between the inverting input end of the operational amplifier main unit and the output end of the operational amplifier main unit, and the output signal processing unit is connected between the output end of the operational amplifier main unit and the microcontroller digital operation unit; The in-phase input unit includes a resistor R1, a resistor R2 and a resistor R3 connected in series in sequence, the resistor R3 is connected in parallel with an electronic switch K1, and a common point of the resistor R1 and the resistor R2 is connected to the in-phase input end of the operational amplifier main unit; the operational amplifier feedback unit includes a capacitor C2 and a resistor R5 and a resistor R6 connected in series with each other, the resistor R6 is connected in parallel with an electronic switch K2, one end of the capacitor C2 is connected to a common point of the resistor R5 and the inverting input end of the operational amplifier feedback unit, and the other end is connected to a common point of the resistor R6 and the output end of the operational amplifier main unit, the inverting input end of the operational amplifier main unit is grounded through R4, and the electronic switch K1 and the electronic switch K2 are commonly connected to the microcontroller digital operation unit; The in-phase input unit is powered by a 1.65V pull-up bias power supply, the positive power supply pin of the operational amplifier main unit is connected to a 3.3V power supply, and the negative power supply pin of the operational amplifier main unit is grounded.

2. A permanent magnet synchronous motor controller for a washing machine according to claim 1, characterized in that: The resistance R1-R6 is governed by the following relationship: R1=R4, R3=R6=(k-1)*R2=(k-1)*R5, where the value of k is 1-7.

3. A permanent magnet synchronous motor controller for a washing machine according to claim 1, characterized in that: The non-inverting input unit includes a capacitor C1 connected to the ground.

4. A permanent magnet synchronous motor controller for a washing machine according to claim 1, characterized in that: The output signal processing unit includes a resistor R7 and a capacitor C3 connected to the ground.

5. A permanent magnet synchronous motor controller for a washing machine according to claim 1, characterized in that: The controller further comprises: A power input unit is used to provide a single-phase mains power interface to the controller; The main circuit unit is used to perform buffering, EMC processing, sorting and smoothing processing on the input power; The bus sampling unit is used to collect the bus voltage of the controller in the current state; The LDO circuit unit performs two-stage voltage reduction on the bus voltage after smoothing to obtain a 15V power supply signal and a 3.3V power supply signal, providing a non-isolated weak power supply signal for the controller; Communication control unit, used for instruction interaction between the user host computer and the microcontroller digital operation unit; The program burning unit is used for the instruction interaction between the manufacturer's host computer and the microcontroller digital operation unit.

6. A permanent magnet synchronous motor controller for a washing machine according to claim 5, characterized in that: The main circuit unit comprises a current limiting resistor and a relay connected in parallel with the current limiting resistor, and the relay is connected to a digital operation unit of a microcontroller.

7. A permanent magnet synchronous motor controller for a washing machine according to claim 1, characterized in that: The inverter unit comprises an intelligent power module IPM and a back-mounted heat sink, wherein the intelligent power module IPM is fixed on the heat sink and is welded on a PCB board.

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